1. Field of the Invention
This invention relates to pressure regulating systems. More specifically, the invention is a pressure regulating system that uses magnetostrictive elements for pressure regulation.
2. Description of the Related Art
Adjustable valves are frequently incorporated in pressure regulating systems. Valve adjustments are typically made under the control of an automated closed-loop feedback system that constantly monitors and regulates pressure. Mechanical feedback based control systems are commonly used. These mechanical pressure regulating systems typically use an adjustable spring or trapped pressure as a reference force to balance the pressure force in a feedback loop. However, these types of devices are difficult to adjust in-situ and generally have large hysteresis and exhibit wide variations in pressure control due to environmental and media temperature ranges, supply pressures, volumes, and other factors.
Adjustable valves using magnetostrictive materials for their actuators are attractive for applications that will experience broad temperature, volume, and supply pressure ranges. The magnetostrictive actuators are moved when a magnetic field is applied thereto. Typically, the magnetic field is generated when electric current flows through one or more coils disposed about the magnetostrictive actuator. Valve adjustments are made by changing the amount of electric current supplied to the coil(s). The resulting flow output of the valve can be sensed (e.g., as a pressure) and then used as a feedback input to a controller that supplies the electric current to the coil(s). If the pressure is to remain steady (i.e., minimal drift from a set-point), small changes in the pressure must be readily and accurately detected with commensurate valve adjustments being quickly implemented.